In April, Barack Obama played host as more than 50 world leaders converged on Washington, DC, for the fourth Nuclear Security Summit. In an op-ed before the summit, Obama argued that “we seek the total elimination one day of nuclear weapons from the face of the Earth.”

North Korea evidently didn’t get the memo. Indeed, it conducted a test missile launch during the summit.

This week, the State Department said the hermit kingdom has restarted production of plutonium fuel, evidence of its continued pursuit of nuclear weapons despite sanctions. A day earlier, the International Atomic Energy Agency (IAEA) announced it saw indications of nuclear activing at North Korea’s Yongbyon facility. And Kim Jong Un’s regime isn’t merely pursuing nuclear capability, but a comprehensive military buildup that should worry its Pacific neighbors and the rest of the world.

For nearly 70 years, and especially over last 20, American presidents have struggled with how to solve a problem like Korea. But Obama’s weakness and starry-eyed college dream of a nuclear-free world — beginning with unilateral disarmament by the West, of course — is making it ever harder to address the growing threat successfully.